In acute stroke, one or more major brain arteries are suddenly occluded, resulting in immediate risk of tissue damage downstream from the site of occlusion. Before the patient arrives at hospital, a volume of tissue will typically already have sustained severe injury with little probability of recovering, while surrounding tissue may be functionally impaired but more likely to regain function if blood flow can be reestablished. Therapeutic strategy is dependent on the volume of this tissue, which is likely to recover.
The relation between acute tissue state and extend of the final infarct is highly complex, and therefore, e.g., Magnetic Resonance Imaging (MRI) is used to gain information on a wide range of tissue characteristics. In the acute setting, an experienced radiologist must investigate a correspondingly large body of image types, in multiple regions of the brain, and based on experience infer the likely tissue response to treatment.
WO 01/56466 A2 describes a method of evaluating novel stroke treatments which includes generating a risk map indicative of the probability of tissue infarction on voxel-by-voxel basis and selecting a probability range for evaluating the therapeutic effect of the novel treatment. In one particular embodiment, tissue having a fifty percent probability of tissue infarction is selected. A novel treatment that has a reduced level of overall actual infarction as compared to the predicted value is indicative of therapeutic effect.
An improved method to generate a risk map indicative of the probability of tissue infarction on a voxel-by-voxel basis would be advantageous, and in particular a more efficient, reliable, fast, reproducible and/or automated method to generate a risk map indicative of tissue infarction on a voxel-by-voxel basis would be advantageous.